Bluetooth
Extended Inquiry Response

This is a guide to the Symbian platform Bluetooth implementation of Extended
Inquiry Response (EIR).

Purpose

EIR provides information about discoverable
devices during a Bluetooth Inquiry.

Intended
audience:

This document is intended to be used by Symbian platform
licensees and third party application developers.

Introduction

A Bluetooth communication connection
is created by two or more devices within a piconet. A device that wishes to
create a connection must find which other devices/services are available.
The Inquiry is a request sent by a Bluetooth-enabled device (the "Inquiring
Device") over a separate physical channel, not within an existing piconet.
The Inquiry requests all listening ("discoverable") Bluetooth devices to identify
themselves. In the standard Inquiry Response each device responds with their
own MAC identifier. The Inquiring Device then has to issue a request to each
device to determine the local name and any services that each device can support.
Supported services may include stereo headset or FTP.

Legacy devices are supported so the set of
responses from all devices may include both EIR and standard Inquiry Responses.

EIR response values

The Extended Inquiry Response
includes the following:

device local name

service class UUIDs
of each service the device supports

the transmission power

manufacturer specific
values

Device
local name

On a device such as a phone handset the device local
name may be set by the user. For example, "Tom's Nokia E71". Otherwise the
local name defined by the manufacturer, for example "MyTech BT Headset". The
EIR data packet is a fixed size so the number of characters available for
the device local name may be insufficient for the entire device local name.
The data sent is as many characters as fit starting with the first character.
The number of characters available depends on how many service IDs are sent
and so this length varies from device to device. A flag is available to indicate
whether the device local name sent is the complete name or a truncated version.

Service class UUIDs of each service the device supports

A
Service Class UUID is a value which identifies a particular type of service/functionality
provided by the device. For example, there would be a Service Class UUID to
identify a printer, and another Service Class UUID to identify a stereo headset.

Transmission Power

A one byte value containing a transmission
power level between -127dBm and +127dBm. The Transmission Power (Tx Power)
value is optional. May be used in conjunction with the Received Signal Strength
Indicator (RSSI) to calculate pathloss and give an estimate of which of two
or more responding devices is physically closer to the Inquiring Device.

Manufacturer specific values

This is a set of 8-bit bytes
and all interpretation and structure is entirely down to the specific manufacturer.